Family House Vejvanov
The heating system is implemented through a combination of radiant panels ECOSUN, underfloor heating foils ECOFILM F and ceiling foils ECOFILM C, ECOFLOOR underfloor heating, and ECOFLEX convectors. The total installed electric heating power is 29.2 kW.
In October 2022, a photovoltaic system (FVE) with a total capacity of 19.8 kWp was installed on the house along with a battery storage system HES with a capacity of 41.1 kWh. The FVE system is divided into two identical parts of 9.9 kWp each. One group of photovoltaic panels is connected directly to the HES storage, while the other group is connected to a separate grid-tied inverter (Fronius) for direct consumption within the building. Surplus electricity from this production section is managed by the battery storage in AC coupling mode. This part of the FVE system is primarily used in the winter season to increase overall production during the heating season. In the summer, this section of the FVE system is turned off, utilizing only the part connected directly to the HES storage. This approach allows for actively limiting or turning off FVE output based on the daily electricity price fluctuations, preventing unwanted grid feed-in during economically unfavorable periods (such as times of zero or negative spot prices).
Previous years' summary data on electricity consumption and costs are available:
| Period | Off-peak Consumption (kWh) |
Peak Consumption (kWh) |
Total Consumption (kWh) |
Total Payment (CZK) |
Unit Price (CZK/kWh) |
|---|---|---|---|---|---|
| 2016/2017 | 20 390 | 714 | 21 104 | 57 384 | 2,72 |
| 2017/2018 | 23 824 | 1 262 | 25 086 | 68 747 | 2,74 |
| 2018/2019 | 22 760 | 1 674 | 24 434 | 73 232 | 2,99 |
| 2019/2020 | 20 931 | 1 170 | 22 101 | 77 069 | 3,48 |
| 2020/2021 | 26 526 | 2 590 | 29 116 | 93 306 | 3,20 |
| 2021/2022 | 25 346 | 1 027 | 26 373 | 116 848 | 4,43 |
| 2022/2023 *) | 21 120 | 3 963 | 25 083 | 156 340 | 6,23 |
*) The amount of consumed energy influenced by the activation of the PV system
From January 2024, the house transitioned to a mode of purchasing and selling electricity based on spot prices (optimized by an algorithm within the HES storage system). Since then, more detailed monthly billing has been available:
| Period | Total consumption (kWh) |
Grid consumption (kWh) |
PV production (kWh) |
Grid feed-in (kWh) |
Grid consumption (CZK) |
Grid feed-in (CZK) |
Electricity costs (CZK) |
Achieved price (CZK/kWh) |
|---|---|---|---|---|---|---|---|---|
| 01/2024 | 4 442 | 3 827 | 756 | 141 | 17 763 | 216 | 16 947 | 3,82 |
| 02/2024 | 3 283 | 2 678 | 722 | 117 | 11 354 | 122 | 11 232 | 3,42 |
| 03/2024 | 2 798 | 1 438 | 1 815 | 455 | 6 346 | 405 | 5 941 | 2,12 |
| 04/2024 | 2 069 | 556 | 2 248 | 735 | 3 116 | 364 | 2 752 | 1,33 |
| 05/2024 | 1 000 | 85 | 2 053 | 1 138 | 1 230 | 1 417 | -187 | -0,18 |
| 06/2024 | ||||||||
| 07/2024 | ||||||||
| 08/2024 | ||||||||
| 09/2024 | ||||||||
| 10/2024 | ||||||||
| 11/2024 | ||||||||
| 12/2024 | ||||||||
| Celkem | 13 592 | 8 584 | 7 594 | 2 586 | 39 209 | 2 524 | 36 685 | 2,69 |
Prices are inclusive of VAT.
Preliminary results for 2024 show that the PV system with HES battery storage, efficiently managed according to spot price trends, is capable of achieving average prices comparable to those from 2016/2017.
